When to use classes?
sbahling at pitnet.net
Sun Mar 5 04:08:55 CET 2000
I am just starting to use python and I love it so far.
I have a couple of philosophical questions about OOP programming with
First: When and when not to create a new class? An example would be if I
have a class for a Polygon, I need to store a set of points defining the
polygon object. One method would be to store a list of tuples containing
the polygon's points. If I want to access the individual x and y coords
of each point, I end up with code that looks like:
firstxcoord = poly.points
firstycoord = poly.points
Or I could create a Point class and use a list of them in the Polygon
class. Then I would have code that looks like:
firstxcoord = poly.points.x
firstycoord = poly.points.y
The second piece of code is easier to read. But lets say that this Point
class has no other purpose but to contain two numerical values; is the
use of a Point class overkill? Is there a 'rule of thumb' for when to
create a new class?
Second: What is the general consensus about accessing instance variables
directly like myobj.x=10 vs. through methods like myobj.setx(10). The
first method is quicker/easier to code, but is it "bad" coding? Does
anyone even care?
I know these are general OOP questions. I am asking in case there are
aspects of the python language that would help to determine when and
when not to do these things.
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